Polymerization

[w-3-r]

hi everybody, i've liked reading through your comments.

hope you can help me now.

i'm not a chemist and i'm going to have to teach polymerization and polymers to 16/17 years old students.

have you any tips to help me teach polymerization and make it easy ---but not so easy that i'm telling white lies? you know where teachers try to make things so easy that they what they say is not longer scientifically true?

[Paul Robbins]

If you have some plastic models available like those in the picture, here is a neat way to explain polymerization.

You and each student should make a model of an ethene (ethylene) molecule.



It's the simplest double-bonded hydrocarbon. After they've done this, ask them to stand in a line, with each of them holding out his or her model.

You stand at the beginning of the line and allow the students to see you take a hydrogen atom, break one of the two C = C bonds in your own ethene molecule, and attach the hydrogen atom so that your molecule now looks like this.



Then bring your molecule close to the first student's model and ask him/her to break the double bond as you did a moment earlier. Then use the free bond on your molecule to join to one of slots that has just become available on the student's molecule. You now have a chain length of 2.

Ask the next student to break the double bond on his/her molecule. Then join your larger molecule to theirs, so that the chain length is 3.

Repeat until all of the students' ethene molecules have become part of the polyethene (polyethylene) polymer molecule.

This is a great, hands-on way of allowing students to see how polymerization works at the molecular level.

[heidi]

What an excellent way to show how polymerization happens. Thanks Paul.

[w-3-r]

i love this, thank you so much paul. we do have model kits and we can do this.